In recent years, a hybrid bone conduction headphone (also referred to as a body-sensitive vibration headphone) having a bone conduction vibration unit mounted in a speaker unit and reproducing a range from a heavy bass sound to middle and high registers have been available in the market. The mounted bone conduction vibration unit compensates a heavy low register that is insufficient in a speaker unit for reproducing middle and high registers. This makes it possible to enjoy a game or a movie with an impressive sound.
On the other hand, a body-sensitive vibration headphone having the bone conduction vibration unit mounted to compensate the high register is disclosed in, for example, PTL 1. PTL 1 discloses a closed type headphone for providing a stimulus to a brain by bone conduction, the closed type headphone having a vibration frequency of 10 kHz or higher and a vibrator attached to an ear pad. In this headphone, vibration from the vibrator directly stimulates a brain and an auditory nerve by bone conduction without passing through an eardrum.